THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



FEBRUARY 1853. 



XIV. On the Refraction of Sound. By C. Sondhauss*. 



DURING several years the thought has been present with 

 me, that sonorous waves expanding in the air must, on 

 passing into another ftiedium in which they possess a different 

 velocity of propagation, undergo a change similar to that suffered 

 by waves of light ; or in other words, that the rays of sound 

 which fall obliquely on the limiting surface of both media must 

 be deflected to or from the normal in a manner similar to the 

 rays of light. To arrive at a decision upon this point, it was 

 necessary to construct a lens-shaped body of such a nature as 

 readily to take up the motion of the sonorous rays, and to con- 

 centrate them by refraction in a point, where the sound might 

 be plainly heard, as it is in the focus of a concave mirror. A 

 lens formed of a solid substance did not appear to me suitable 

 for the purpose. The thought of forming a lens-shaped bladder 

 from a thin membrane therefore occurred to me ; this bladder, 

 when filled with a gas of greater density than the air, for ex- 

 ample with carbonic acid, might furnish a convex lens suitable 

 for the refraction of sound. 



As a first experiment, I made use of an air-balloon of gold- 

 beater's skin, about a foot in diameter. After having filled it 

 with carbonic acid I suspended it freely ; fixed at a distance of 

 about a foot from it a weak-ticking watch, and listened at the 

 opposite side of the balloon, in the direction of its axis, to the 

 ticking. As often as I made the experiment, I thought I heard 

 the ticking for a distance of several feet behind the balloon, in 



* From Poggendorff *s Annalen, vol. Ixxxv. p. 378. ■> 



Phil, Mag. S. 4. Vol. 5. No. 30. Feb. 1853. G 



